Type III deiodinase inhibitors and uses thereof

ABSTRACT

The present invention relates to compounds that inhibit the activity of Type III deiodinase (DIO3). The present invention further relates to methods for treating or preventing depression, depression associated with other psychiatric or general medical diseases or conditions, condition amenable to treatment with known anti-depressants and cancer, particularly by using the compounds of the invention.

CROSS REFERENCE TO RELATED APPLICATION

This application is a 35 U.S.C. 371 National Phase Entry Applicationfrom PCT/IL2015/050277, filed Mar. 16, 2015, which claims the benefit ofU.S. Provisional Application Nos. 61/953,846 filed on Mar. 16, 2014 and62/097,142 filed on Dec. 29, 2016, the disclosure of which areincorporated herein in their entirety by reference.

FIELD OF THE INVENTION

The present invention relates to compounds that inhibit the activity ofType III deiodinase (DIO3) and to the use of DIO3 inhibitors fortreating or preventing depression, depression associated with otherdisorders or conditions, and cancer.

BACKGROUND OF THE INVENTION

Mood disorders are among the most prevalent forms of mental illness.Severe forms of mental illness affect 2%-5% of the US population and upto 20% of the population suffers from milder forms of the illness. Theeconomic costs to society and personal costs to individuals and familiesare enormous.

Depressive syndromes occur in the context of a vast number of mental andmedical illnesses. Depression is a central feature of major depressivedisorder and bipolar disorder. Anxiety disorders, such as post-traumaticstress disorder (PTSD), obsessive-compulsive disorder, panic disorder,social phobia, and generalized anxiety disorder, are often accompaniedby depression. Alcohol and other substance abuse or dependence may alsoco-exist with depression. Research shows that mood disorders andsubstance abuse commonly occur together. Depression also may occur withother serious medical illnesses such as heart disease, stroke, cancer,HIV/AIDS, diabetes, and Parkinson's disease. People who have depressionalong with another medical illness tend to have more difficulty adaptingto their medical condition, and more medical costs than those who do nothave co-existing depression. Treating the depression can also helpimprove the outcome of treating the co-occurring illness.

There are several forms of depressive disorders. Major depressivedisorder, or major depression, is characterized by a combination ofsymptoms that interfere with a person's ability to work, sleep, study,eat, and enjoy once-pleasurable activities. Major depression isdisabling and prevents a person from functioning normally. Some peoplemay experience only a single episode within their lifetime, but moreoften a person may have multiple episodes.

Currently available pharmacological treatments for major depression areseverely limited in their efficacy (Rush A J et al. Am J Psychiatry2006; 163, 1905-1917). No more than a third of patients achieveremission on standard treatment and at least a third remains ill after ayear or more of serial treatments.

The hormone L-3,3′,5,5′,-tetraiodothyronine (L-thyroxine or T4) is aproduct of the thyroid gland. Although thyroxine (tetraiodothyronine;T4) is the principal secretory product of the vertebrate thyroid, it'sessential metabolic and developmental effects are primarily mediated by3,3′,5-triiodothyronine (T3), which is produced from the prohormone by5′-deiodination.

T4 is converted by one of three selenium-containing enzymes(deiodinases) into either the active hormone L-3,3′,5,-triiodothyronine(T3), the inactive T3 competitive product L-3,3′,5′-triiodothyroninereferred to as reverse T3 (rT3) or, indirectly (by first being convertedto T3) to the deactivated L-3,3′-diiodothyronine (3,3′-T2). Type Iiodothyronine deiodinase (DIO1), a thiol-requiringpropylthiouracil-sensitive oxidoreductase, is found mainly in liver andkidney and catalyzes conversion of T3 and rT3 by deiodination of thephenolic ring 5′ position iodine to form T3 or deiodination of thetyrosyl ring 5 position iodine to form rT3. Type II deiodinase (DIO2) isresponsible for intracellular deiodination and its activity is limitedto phenolic ring 5′ position deiodination to form T3 from T4. While theactivity of DIO2 is similar to that of DIO1, DIO2 is primarily found inthe thyroid, pituitary gland, brain, brown fat and testis. Type IIIdeiodinase (DIO3) activity is limited to inner ring deiodination of T4and T3 to the inactive rT3 and T2 products, respectively. DIO3 isprimarily found in the brain, and can further be found in fetal tissues,placenta, skin and adipose tissue. DIO3 is not found in the heart or inbones. These reactions are illustrated in FIG. 1.

T3 is metabolically active and stimulates production of cellular energy,and generally is an activator of tissues and organs. T3 acts bydiffusing into cells, where it interacts with a cellular protein whichtransports the T3 to the cellular nucleus. T3 then acts by stimulatinggene transcription to produce messenger ribonucleic acids (mRNA) ofcertain genes. Translation of the T3-induced mRNA produces cellularproteins that promote cellular activation. In contrast, rT3 has opposingeffects, at least partially by inhibiting the action of T3, by way ofcompetitively inhibiting T3 nuclear receptors in cells.

The thyroid hormone, triiodothyronine (T3), is widely used to augmentantidepressant action in depressed patients who have not responded totreatment with conventional antidepressants. While T3 is rarely usedclinically as a monotherapy, the inventors of the present invention andco-workers have shown that chronic administration of the hormone has adose dependent, antidepressant-like effect using screening testsincluding the forced swim test (FST), tail suspension test (TST) andnovelty suppressed feeding test (NSFT) in mice (Lifschytz T et al. J.Pharmacol. Exp. Ther. 2011; 337, 494-502). Using in vivo microdialysisit has been also shown that chronic administration of T3 enhancesserotonergic neurotransmission in rat frontal cortex and hypothalamus byfunctional desensitization of presynaptic 5-HT1A and 5-HT1B receptorswhich inhibit serotonin release (Lifschytz T et al. Curr. Drug Targets2006; 7, 203-210). Moreover, when administered concurrently withfluoxetine (an anti-depressant also known by the tradename Prozac), T3enhances neurogenesis in the rat hippocampus over and above the effectof fluoxetine alone (Eitan, R et al. Int J. Neuropsychopharmacol. 2010;13, 553-561).

Although it has been suggested that administration of T3 can overcomedepression symptoms it is not feasible to use T3 or synthetic analogsthereof as a first line treatment for depression because the hormone hassignificant effects on heart rate and bone density that limit long termuse. Moreover, it has been recently shown that in mice theantidepressant effects of T3 are mediated by the same thyroid receptorsubtypes responsible for T3 effects on heart rate and bone density(Lifschytz et al. 2011, ibid).

High expression of DIO3 with a crucial role in sustaining cellproliferation has been documented at sites of local inflammation, in theinfarcted heart, during liver regeneration and in peripheral nervesafter injury. DIO3 has also been shown to be re-expressed in variousneoplastic tissues while remaining silent in the normal counterparttissues. Elevated DIO3 mRNA and activity levels were shown in a varietyof cancer cell lines including endometrium, neuroblastoma, colon, liver,basal cell carcinomas and breast cancer (Dentice M et al., Expert OpinTher Targets, 2013; 17(11), 1369-79; Luongo C et al., Endocrinology2014; 155(6), 2077-88) and in a number of human brain tumors (Nauman Pet al., Folia Neuropathol 2004; 42(2), 67-73.). DIO3 expression has beenfound to be under the control of several signaling molecules andpathways that are major driving forces of cellular division, includingHIF-1α, TGF and the Wnt-β-catenin pathway (Dentice M et al., JEndocrinol, 2011; 209(3), 273-82). It is thus proposed that DIO3 isunder the control of an intricate circuit of signaling pathways thatplay a central role in the oncogenic process.

Elevating T3 concentration or the ratio of active T3 to non-active rT3for treating various disorders has been suggested.

For example, PCT Patent Application Publication No. WO 03/099105discloses methods for diagnosis and treatment of several disorderscharacterized by elevated serum ratio of rT3 to T3 defined as humandormancy syndrome. The treatment of human dormancy syndrome is directedtoward increasing functional T3 levels or decreasing the inactive rT3levels, or both, using pharmaceutical and/or behavioral methods,particularly via the modulation of type I deiodinase activity.Exemplified therein is the effect of T3 administration of several humandormancy syndrome disorders, depression being listed among the manyother of the manifestations of this syndrome.

PCT Patent Application Publication No. WO 2006/028835 discloses the useof thyroid hormone conversion inhibitors to treat hyperproliferativeskin disorders, preferably their use in topical admixtures.Particularly, the invention discloses the use of deiodinase inhibitorssuch as an iodinated contrast agent, e.g., iopanoic acid (IOP) and/orits analogs.

PCT Patent Application Publication No. WO 2008/140713 discloses methodsfor regulating the levels of type 3 iodothyronine deiodinase (DIO3) andor thyroid hormone in cancerous and pre-cancerous cells and relatedcompositions and kits. siRNA and antisense oligonucleotides aresuggested as DIO3 inhibitors.

PCT Patent Application Publication No. WO 2009/015366 discloses methodsof treating conditions associated with hyperproliferation of cells, suchas hirsutism, hypertrichosis, scar formation, ocular hyperproliferativedisease, and pulmonary hyperproliferative disease, comprisingadministering thyroid hormone conversion inhibitor. In particularembodiments, the thyroid hormone conversion inhibitor is selected fromthe group consisting of iopanoic acid (IOP), ipodate, and propranolol.

Stoedter et al., published after the priority of the present invention,describe the effect of several selenocompounds containing a methyl- orbenzyl-imidoselenocarbamate backbone on DIO expression in cancerouscells in vitro. A deferential effect was observed with the compoundsexamined, highlighting that these selenocompounds may constituteinteresting pharmacological compounds for modifying DIO expression,potentially affecting the balance between cell differentiation andproliferation (Stoedter et al., Metallomics 2015; 7(2), 347-54).

U.S. Pat. No. 8,304,401 discloses methods for decreasing fat mass,increasing energy expenditure, increasing resistance to obesity, andlowering blood glucose levels in a subject with an agent that inhibitsthe expression or activity of type III deiodinase (DIO3). The inhibitingagent is an antisense, siRNA, siRNA-like, or ribozyme molecule and theagents of the invention are useful in treating diabetes and obesity.

An inventor of the present invention and co-workers have extensivelystudied the deiodination of thyroxine and related compounds, and haverecently reported the first examples of synthetic compounds thatfunctionally mimic DIO3 activity (FIG. 2) (Manna and Mugesh, Angew.Chem. Int. Ed. 2010; 49, 9246-9249; Manna and Mugesh, J. Am. Chem. Soc.,2011, 133, 9980-9983; Manna and Mugesh, J. Am. Chem. Soc. 2012; 134,4269-4279).

To date, no effective specific inhibitors for Type III deiodinase (DIO3)are used as therapeutic compounds. DIO3 specific inhibitors could beefficient in treating diseases in which attenuating the expressionand/or activity of this enzyme is desired, including depression in thecontext of major depressive disorder and bipolar disorder and depressionassociated with other diseases or conditions, and cancer.

There is an ongoing need for and it would be highly advantageous to havedrugs which would inhibit cancerous states. Further, there is a criticaland ongoing need for drugs for treating neuropsychiatric disorders anddepression associated conditions that are specific and have minimaldeleterious side effects.

SUMMARY OF THE INVENTION

The present invention relates to compounds that inhibit the activity ofType III deiodinase (DIO3). The present invention further relates tomethods for treating or preventing undesired conditions in whichattenuating the activity of DIO3 have a beneficial effect, particularlyby administering the compounds of the present invention.

The present invention is based in part on a novel system for identifyingsmall molecules capable of specifically inhibiting DIO3, utilizingsynthetic compounds that functionally mimic the DIO3 activity. Aninventor of the present invention and co-workers have previouslyreported that naphthyl-based compounds having two selenols in theperi-positions exhibit deiodinase activity and thus act as DIO3 mimics(Manna and Mugesh 2010, ibid; Manna and Mugesh 2011 ibid; Manna andMugesh 2012, ibid). These compounds (See, e.g. compound A, FIG. 3) havebeen shown to behave similarly to DIO3 with respect to deiodination.Namely, the compounds remove iodine selectively from the tyrosyl ring ofT4 or T3 and produce rT3 and 3,3′-T2, respectively (FIG. 2).

In view of those findings, DIO3 mimics were used as powerful tools forthe design of compounds that specifically inhibit the DIO3 enzyme andthus are useful in the treatment of conditions where attenuation of DIO3expression or activity provides a beneficial outcome, including centralnervous system (CNS) diseases, depression and depression associated withother conditions and in the treatment of conditions implicated withundesired expression or activity of DIO3, for example diseasesassociated with cell overproliferation, particularly cancer.

The compounds so identified are useful in inhibiting DIO3 activity.

Without being bound by any theory or mechanism of action, the compoundsof the invention increase the endogenous amounts of T3 by inhibitingDIO3 activity, which catalyzes conversion of the active hormone3,5,3′-triiodothyronine (T3) to the inactive metabolite T2.

The teachings of the present invention are advantageous over thehitherto known direct use of T3 as antidepressant, as chronicadministration of T3 is associated with deleterious side effects,including enhancement of bone depletion, muscle weakness andtachycardia. To the contrary, the selective inhibition of DIO3, known tobe primarily active in the brain, results in the desired effect ofalleviating depression and associated conditions while having a minoreffect on the heart, bones and muscles. DIO3 has also been correlatedwith hyperproliferative states and solid tumors, and thus specificinhibition of DIO3 is advantageous for treating these conditions.

It is contemplated that the ability of a compound to simultaneouslyreact with both selenol moieties of the DIO3 mimic provides for itsspecific inhibition of DIO3. Based on this, the applicants designed andsynthesized maleimide-based compounds of formula (I), which are linkedto a phenylcarboxylic acid (e.g., p-benzoic acid or iopanoic acid)moiety (as exemplified in Formula II), or to a side chain or an aminoacid, e.g., tyrosine (as exemplified in Formula III). The twosimultaneous nucleophilic attacks of the selenol moieties at the carbonsadjacent to the carbonyl groups of the maleimide derivatives areexpected to block the selenium centers by forming a stable adduct, thusleading to inhibition of deiodinase activity. In some embodiments, thecompounds were advantageously designed to be water soluble.

Thus, according to one aspect, the present invention provides a compoundhaving the general formula I:

wherein

-   -   A is

-   -   R¹ is independently at each occurrence a halogen, OH, NO₂ or        N(R)₂ wherein    -   each R is independently H or a C₁-C₆ alkyl;    -   R² is COOH, OH, NO₂, N(R)₂ or a linear or branched C₁-C₆ alkyl        substituted with at least one group selected from the group        consisting of COOH, halogen, OH, NO₂, and N(R)₂;    -   R³ is H or COOH;    -   R⁴ is iodophenyl, heterocyclyl, heteroaryl, or the side chain of        an amino acid selected from the group consisting of tyrosine,        3,4-dihydroxyphenylalanine (DOPA), iodotyrosine, aspartic acid,        valine, leucine, isoleucine, methionine, tryptophan, threonine,        asparagine, glutamine, cysteine, proline, arginine, histidine,        lysine, glutamic acid; or R⁴ is represented by the structure:

-   -   wherein R⁵ is independently at each occurrence OH, halogen, NO₂        or N(R)₂ and m is 0, 1, 2, 3 or 4;    -   L¹ and L² are each a leaving group selected from a halogen and a        sulfonate;    -   n is 1, 2, 3 or 4;    -   and salts thereof.

In one embodiment, the compound of formula (I) is a phenylcarboxylicacid derivative (e.g., p-benzoic acid derivative or iopanoic acidderivative), represented by the structure of formula (II):

In some embodiments, n=0 in compound (II), and R¹ does not exist. Inother embodiments, however, the phenyl ring is substituted with one ormore halogens, OH, NO₂ or N(R)₂ wherein each R is independently H or aC₁-C₆ alkyl. In accordance with this embodiment, n in formula (II) is 1,2, 3 or 4, preferably 2 or 3. In one embodiment of formula (II), R¹ ishalogen, preferably a bromine or iodine. In another embodiment offormula (II), R¹ is OH. In another embodiment of formula (II), n is 2 or3, and R¹ is iodine. Each possibility represents a separate embodimentof the present invention.

In one embodiment of formula (II), R² is COOH, which can be in theortho, meta or para position, and preferably in the para position. Inaccordance with this embodiment, compound (II) is a benzoic acidderivative, preferably a p-benzoic acid derivative. In anotherembodiment of formula (II), R² is OH (i.e., the compound is a phenolderivative). The OH can be positioned anywhere on the ring. In anotherembodiment of formula (II), R² is a linear or branched C₁-C₆ alkylsubstituted with a COOH at any location. In one currently preferredembodiment, R² is —CH₂CH(COOH)CH₂CH₃. In accordance with thisembodiment, the compound is derived from iopanoic acid. Each possibilityrepresents a separate embodiment of the present invention.

In another embodiment, the compound of formula (I) is represented by thestructure of formula (III):

In one embodiment of formula (III), R⁴ is the side chain of tyrosine. Inanother embodiment of formula (III), R⁴ is the side chain of3,4-dihydroxyphenylalanine (also designated 3-hydroxy tyrosine or DOPA).In another embodiment of formula (III), R⁴ is the side chain of3,5-diiodotyrosine. In another embodiment, R⁴ is represented by thestructure:

wherein R⁵ is OH, halogen, NO₂ or N(R)₂ and m is 0, 1, 2, 3 or 4.

In some embodiments of formula (III), m=0 and R⁵ does not exist. Inother embodiments, however, the phenol ring is substituted with one ormore hydroxyls (OH), halogens (preferably bromine or iodine), NO₂ and/orN(R)₂. In accordance with this embodiment, m in formula (I) is 1, 2, 3or 4, preferably 1, 2 or 3. Each possibility represents a separateembodiment of the present invention.

In another embodiment of formula (III), R⁴ is iodophenyl which isselected from 2-iodophenyl, 3-iodophenyl and 4-iodophenyl. In anotherembodiment, R⁴ is tetrahydrofuryl. Each possibility represents aseparate embodiment of the present invention.

In another embodiment of formula (III), R⁴ in formula (I) is the sidechain of aspartic acid, i.e., —CH₂—COOH. In another embodiment, R⁴ isthe side chain of an amino acid selected from the group consisting ofvaline, leucine, isoleucine, methionine, tryptophan, threonine,asparagine, glutamine, cysteine, proline, arginine, histidine, lysineand glutamic acid.

In another embodiment, the compound is an ethyl diiodophenol, iodobenzylor tetrahydrofuryl derivative, represented by the structure of formula(III).

The L¹ and L² substituents in Formula (I) or (II) are leaving groupsselected from a halogen (preferably Br or I) or a sulfonate representedby the structure OSO₂R′ wherein R is an alkyl or aryl (e.g., OAc(0-acetate), OTs (tosylate), OMs (mesylate), OTf (triflate)). PreferredL¹ and L² substituents are halogens, especially bromine.

According to another aspect, the present invention provides apharmaceutical composition comprising the compounds of the presentinvention, which are represented by Formula (I) or (II), e.g., compounds3, 5, 6, 7, 8, 9, 10, 11 or 12, further comprising a pharmaceuticallyacceptable diluent or carrier.

According to yet an additional aspect, the present invention provides amethod for treating or preventing depression, the method comprisesadministering to a subject in need thereof a therapeutically effectiveamount of a compound that inhibits the activity of Type III deiodinase(DIO3) thereby treating or preventing depression.

According to certain exemplary embodiments, the method comprisesadministering to a subject in need thereof a therapeutically effectiveamount of at least one compound of the invention as described hereinthat inhibits the activity of Type III deiodinase (DIO3) or apharmaceutical composition comprising same, thereby treating orpreventing depression.

According to further aspect, the present invention provides a compoundthat inhibits the activity of Type III deiodinase (DIO3) or apharmaceutical composition comprising same for use in the treatment orprevention of depression or a depression associated disease or disorder,wherein said compound inhibits the activity of Type III deiodinase(DIO3).

According to certain exemplary embodiments, the compound that inhibitsthe activity of Type III deiodinase (DIO3) is a compound according tothe teachings of the present invention.

According to some embodiments, the depression is associated with acondition selected from the group consisting of major depressivedisorder and bipolar disorder. Each possibility represents a separateembodiment of the present invention.

According to other embodiments, the depression is associated with otherpsychiatric disorders selected from the group consisting of dysthymia,posttraumatic stress disorder, post-partum depression, schizophrenia,schizoaffective disorder, anxiety disorder (including obsessivecompulsive disorder, generalized anxiety disorder, panic disorder andsocial phobia), eating disorders including anorexia nervosa and bulimia,Parkinson's disease, Alzheimer's disease, fibromyalgia and chronicfatigue syndrome. Each possibility represents a separate embodiment ofthe present invention.

According to yet additional embodiments, the depression is associatedwith a general medical condition selected from the group consisting ofheart disease, cancer, diabetes, HIV/AIDS and neurological conditions(including stroke and multiple sclerosis). Each possibility represents aseparate embodiment of the present invention.

According to further embodiments, the depression is associated withalcohol and/or drug abuse.

According to additional aspect, the present invention provides a methodfor treating a subject affected with or susceptible to be affected withat least one of obsessive compulsive disorder, panic disorder,generalized anxiety disorder, pre-menstrual syndrome (PMS),posttraumatic stress disorder, social phobia, agoraphobia, fibromyalgia,chronic fatigue syndrome chronic pain, bulimia, anorexia nervosa,obesity, alcohol abuse, smoking cessation and nicotine withdrawalsyndrome symptoms the method comprises administering to the subject atherapeutically effective amount of a compound that inhibits theactivity of Type III deiodinase (DIO3) or a pharmaceutical compositioncomprising same. Each possibility represents a separate embodiment ofthe present invention.

According to certain exemplary embodiments, the compound that inhibitsthe activity of Type III deiodinase (DIO3) is a compound of the presentinvention as described herein.

According to yet additional aspect, the present invention provides amethod for treating or preventing cancer, the method comprisesadministering to a subject in need thereof a therapeutically effectiveamount of the compound of the invention that inhibits the activity ofType III deiodinase (DIO3) or a pharmaceutical composition comprisingsame, thereby treating or preventing cancer.

According to certain embodiments, the cancer is selected from the groupconsisting of ovarian cancer, endometrial cancer, neuroblastoma, coloncancer, hepatic cancer, basal cell carcinoma and breast cancer. Eachpossibility represents a separate embodiment of the present invention.

According to certain exemplary embodiments, the cancer is ovariancancer.

According to certain embodiments, inhibition of DIO3 activity results inincreased amount of T3 in the subject. According to currently certainexemplary embodiments, the amount of T3 is increased in the brain of thesubject.

According to certain embodiments, the treatment results in adiminishment or elimination of depression and/or its symptoms.

Compounds useful in treating and/or preventing any of the diseases orconditions described herein are compounds of formula (I), for examplecompounds of formulae (II) or (III) as exemplified herein. Additionalcompounds useful in treating and/or preventing any of the diseases orconditions described herein are compounds of formula (I-A):

wherein

-   -   A is

-   -   R¹ is independently at each occurrence a halogen, OH, NO₂ or        N(R)₂ wherein each R is independently H or a C₁-C₆ alkyl;    -   R² is COOH, OH, NO₂, N(R)₂ or a linear or branched C₁-C₆ alkyl        substituted with at least one group selected from the group        consisting of COOH, halogen, OH, NO₂, and N(R)₂;    -   R³ is H or COOH;    -   R⁴ is iodophenyl, heterocyclyl, heteroaryl, the side chain of an        amino acid selected from the group consisting of a naturally        occurring alpha-amino acid, 3,4-dihydroxyphenylalanine (DOPA)        and iodotyrosine; or R⁴ is represented by the structure:

-   -   wherein R⁵ is independently at each occurrence OH, halogen, NO₂        or N(R)₂ and m is 0, 1, 2, 3 or 4;    -   L¹ and L² are each a leaving group selected from a halogen and a        sulfonate;    -   n is 0, 1, 2, 3 or 4;    -   and salts thereof.

Currently preferred compounds according to the present invention arerepresented by the structure of formula 3, 4, 5, 6, 7, 8, 9, 10, 11 or12, with each possibility representing a separate embodiment of thepresent invention.

-   -   and salts thereof.

Each of said compounds can be used alone or in a pharmaceuticalcomposition in the context of the present invention.

According to certain typical embodiments, the compound specificallyinhibits the activity of DIO3. Typically, the compound is identifiedaccording to the teachings of the present invention and has the generalformula I or II or III or I-A, or any of the compounds encompassed forsuch formulae as disclosed herein. However, it is to be explicitlyunderstood that other compounds having specificity to DIO3 inhibitionare encompassed within the scope of the present invention.

According to other typical embodiments, the subject is human.

Other objects, features and advantages of the present invention willbecome clear from the following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 demonstrate activation and inactivation of thyroid hormones bythe three iodothyronine deiodinases DIO1 (ID-1), DIO2 (ID-2) and DIO3(ID-3).

FIG. 2 shows inner ring monodeiodination of T4 to rT3 or of T3 to3,3′-T2 by DIO3 mimic (compound A).

FIG. 3 demonstrates deiodination of thyroxine by compound A, a DIO3mimic.

FIG. 4 shows Inhibition of DIO3 mimic by Compound C(Dibromo-N-methylmaleimide).

FIG. 5 shows Inhibition of DIO3 mimic by Compound 3(2,3-dibromo-N-3-(4-hydroxyphenyl)propanoic acid) maleimide; TYR-DBRMD).

FIG. 6 shows ¹H NMR spectra of compound 3 in DMSO-d₆.

FIG. 7: shows ¹³C NMR spectra of compound 3 in DMSO-d₆.

FIG. 8 shows ¹H NMR spectra of compound 4 in DMSO-d₆.

FIG. 9 shows ¹³C NMR spectra of compound 4 in DMSO-d₆.

FIG. 10 is a bar graph showing brain T3 levels (pg/ml) followingintracerebroventricular (ICV) administration of IOP-DIBRMD(2,3-dibromo-N-2,4,6-triiodobenzyl)butanoic acid)maleimide; IOP,compound 6) by osmotic minipumps for 3 weeks (*Significant; One sided,non-paired t test).

FIG. 11 is a bar graph showing the effect of IOP-DIBRMD (IOP, compound6) on latency to feed in the novelty suppressed feeding test. Marginalmeans derived from the ANCOVA are shown. The effect of T3 in the modelis significant (F=6.21; p=0.026).

FIG. 12 is a bar graph showing the effect of ITYR-DIBRMD(2,3-dibromo-N-3-(4-hydroxy-3,5-diiodophenyl)propanoic acid) maleimide;ITYR, compound 5) on latency to feed in the novelty suppressed feedingtest. Marginal means derived from the ANCOVA are shown. Animals treatedwith IOP show a reduced latency to feed. Model shows significance(F=7.23; p=0.006). Effect of T3 in the model is significant (F=7.62;p=0.01).

FIG. 13A shows DIO3 expression in ovarian cancer cells (A2780, SKOV3 andOVCAR3 cell lines) as measured by FACS analysis.

FIG. 13B demonstrated the effect of compounds C1-C6 on the density ofthe ovarian cancer cell line OVCAR3. Cells were treated with 0.5 μM DIO3inhibitors for 48 h and imaged by light microscopy.

FIG. 13C demonstrated the effect of compounds C1-C6 on the viability ofthe ovarian cancer cell line OVCAR3. Cells were treated with 0.5 μM DIO3inhibitors for 48 h and analyzed by WST-1 viability assay.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel compounds that specifically inhibitthe activity of Type III deiodinase (DIO3). DIO3 is particularly activein the brain, and DIO3 inhibition may thus result in an increased amountof the hormone 3,3′,5,-triiodothyronine (T3) in brain. DIO3 has alsobeen indicated to be associated with hyperproliferative states and withhuman solid tumors. Specifically, previous studies reported elevatedexpression and activity of DIO3 in a number of human cancer diseases(Dentice et al. 2013, ibid).

The present invention discloses for the first time that inhibition ofDIO3 activity is useful for treating and/or preventing depression.Without wishing to be bound by certain specific theory or mechanism ofaction, inhibition of DIO3 by the compounds of the invention leads toelevated content of T3 in the brain. The novel compounds of the presentinvention are also useful for treating and/or preventing cancer andother diseases or disorders associated with elevated expression oractivity of DIO3.

Definitions

The term “C₁-C₆ alkyl” as used herein alone or as part of another grouprefers to any saturated aliphatic hydrocarbon, including straight-chain,and branched-chain which contains 1 to 6 carbon atoms. Examples of C1-C6alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, isobutyl, t-butyl, 1-phenyl, 2-pentyl, 3-pentyl, 1-hexyl,2-hexyl, and 3-hexyl. According to the principles of the presentinvention, the C1-C6 alkyl group is substituted at any location with aCOOH moiety.

The term “tyrosine side chain” refers to the following moiety:

The term “iodotyrosine side chain” refers to a tyrosine side chain inwhich one or more of the phenyl hydrogens have been substituted byiodine. One non-limiting example of an iodotyrosine side chain is a3-5-diiosotyrosine group represented by the moiety:

The term “hydroxytyrosine side chain” refers to a tyrosine side chain inwhich one or more of the phenyl hydrogens have been substituted by ahydroxy. One non-limiting example of a hydroxytyrosine side chain is3-hydroxytyrosine group (alternatively designated3,4-dihydroxyphenylalanine), which is represented by the moiety:

also known as “DOPA”.

The term “aspartic acid side chain” refers to the group —CH₂—COOH.

The term “ethyl diiodophenol” refers to an ethylphenol group in whichtwo of the phenol hydrogens have been substituted by iodine. Onenon-limiting example of an ethyl diiodophenol is represented by themoiety:

Several of the compounds of the present invention contain side chains ofnaturally occurring alpha-amino acids. The naturally occurring aminoacids are, e.g., glycine, alanine, valine, leucine, isoleucine, serine,methionine, threonine, phenylalanine, tyrosine, tryptophan, cysteine,proline, histidine, aspartic acid, asparagine, glutamic acid, glutamine,γ-carboxyglutamic acid, arginine, ornithine and lysine. Each possibilityrepresents a separate embodiment of the present invention.

The term “depression” as used herein includes, but is not limited to,major depressive episodes in the context of major depressive disorder orbipolar disorder, schizoaffective disorder and other psychiatric statesthat are characterized by depressed mood and/or feelings of sadness,despair, discouragement, “blues”, melancholy, feelings of low selfesteem, guilt and self reproach, withdrawal from interpersonal contact,and somatic symptoms such as eating and sleep disturbances.

It is to be explicitly understood that the present invention encompassestreating depression that is associated with other psychiatric disorders,with general medical conditions or with alcohol or drug abuse.

Examples of other psychiatric disorders that may be associated withdepression include, but are not limited to, dysthymia, posttraumaticstress disorder, schizophrenia, schizoaffective disorder, post-partumdepression, eating disorders including anorexia nervosa and bulimia,anxiety disorders, Parkinson's disease, Alzheimer's disease,fibromyalgia and chronic fatigue syndrome.

Anxiety disorders include, but are not limited to, obsessive compulsivedisorder, generalized anxiety disorder, panic disorder and socialphobia.

Examples of general medical conditions associated with depressioninclude, but are not limited to, heart diseases, cancer, diabetes,HIV/AIDS and neurological conditions such as stroke and multiplesclerosis.

The present invention also encompasses treating disease and conditionsknown to be amenable to treatment with anti-depressants other than thecompounds of the present invention. According to certain embodiments,such diseases or conditions include, but are not limited to, obsessivecompulsive disorder, panic disorder, generalized anxiety disorder,pre-menstrual syndrome (PMS), posttraumatic stress disorder, socialphobia, agoraphobia, fibromyalgia, chronic fatigue syndrome chronicpain, bulimia, anorexia nervosa, obesity, alcohol abuse, smokingcessation and nicotine withdrawal syndrome symptoms.

The term “cancer” refers to a medical condition characterized byabnormal cell growth in a tissue. The term encompasses a wide range ofcancers, classified according to cell type origin, including, withoutlimitation, carcinomas, sarcomas, myelomas, leukemias and lymphomas.Particular types of cancers, classified according to the affectedtissue, include, without limitation, brain cancer, lymphoproliferativedisorders, breast cancer, ovarian cancer, prostate cancer, cervicalcancer, endometrial cancer, bone cancer, liver cancer, stomach cancer,colon cancer, pancreatic cancer, cancer of the thyroid, head and neckcancer, cancer of the central nervous system, cancer of the peripheralnervous system, skin cancer, and kidney cancer. Further cancer types,include, without limitation, hepatocellular carcinoma, hematoma,hepatoblastoma, rhabdomyosarcoma, esophageal carcinoma, thyroidcarcinoma, ganglioblastoma, fibrosarcoma, myxosarcoma, liposarcoma,chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma,endotheliosarcoma, Ewing's tumor, leimyosarcoma, rhabdotheliosarcoma,invasive ductal carcinoma, papillary adenocarcinoma, melanoma, squamouscell carcinoma, basal cell carcinoma, adenocarcinoma (welldifferentiated, moderately differentiated, poorly differentiated orundifferentiated), renal cell carcinoma, hypernephroma, hypernephroidadenocarcinoma, bile duct carcinoma, choriocarcinoma, seminoma,embryonal carcinoma, Wilms' tumor, testicular tumor, lung carcinomaincluding small cell, non-small and large cell lung carcinoma, bladdercarcinoma, glioma, astrocyoma, medulloblastoma, craniopharyngioma,ependymoma, pinealoma, retinoblastoma, neuroblastoma, colon carcinoma,rectal carcinoma, hematopoietic malignancies including all types ofleukemia and lymphoma including: acute myelogenous leukemia, acutemyelocytic leukemia, acute lymphocytic leukemia, chronic myelogenousleukemia, chronic lymphocytic leukemia, mast cell leukemia, multiplemyeloma, myeloid lymphoma, Hodgkin's lymphoma, non-Hodgkin's lymphoma.

According to some embodiments, the cancer is associated with aberrantDIO3 expression. A cancer associated with aberrant expression of DIO3 isone in which DIO3 expression or activity results in a level of activeDIO3 that is greater than that observed in corresponding (similar celltypes) non-cancerous cells. In other embodiments, it is a cancerassociated with low levels of active T3. A cancer associated with lowlevels of T3 is one in which functional or active T3 is lower than in acorresponding non cancerous cell.

According to certain embodiments, the compounds of the invention are fortreating solid tumors.

As used herein, the terms “type III deiodinase”, “type III iodothyroninedeiodinase”, type 3 deiodinase”, “type 3 iodothyronine deiodinase”, DIO3and D3 are used herein interchangeably and refer to a protein belongingto the iodothyronine deiodinase family that catalyzes the inactivationof thyroid hormone by inner ring deiodination of the prohormonethyroxine (T4) and the bioactive hormone 3,3′,5-triiodothyronine (T3) toinactive metabolites, 3,3′,5′-triiodothyronine (rT3) and3,3′-diiodothyronine (3,3′-T2), respectively.

As used herein, the term “inhibition” with regard to inhibiting theactivity of DIO3 refers to reducing the activity of DIO3 compared to itsactivity under the same conditions without the addition of an inhibitorycompound. According to certain embodiments, the DIO3 activity is reducedby at least 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99% or100% compared to its activity under the same conditions without theaddition of an inhibitory compound. Each possibility represents aseparate embodiment of the present invention.

The term “specific inhibition” with regard to the inhibition of DIO3 bythe compounds of the present invention refers to compounds which inhibitDIO3 to a greater extent (e.g., a lower K_(i)) than it inhibits DIO2 orDIO1 enzymes. A specific DIO3 inhibitor also includes agents thatinhibit DIO3, but fail to inhibit DIO2 or DIO1 at comparableconcentrations.

The term “therapeutically effective amount” refers to the amount of acompound of the present invention that, when administered to a subjectin need thereof, results in inhibition of DIO3 activity. According tocertain embodiments, inhibition of DIO3 activity results in increased T3amounts in the brain compared to the amounts observed in other organs.

The term “preventing” as used herein means causing the clinical symptomsof the disease state not to develop in a subject that may be exposed toor predisposed to the disease state, but does not yet experience ordisplay symptoms of the disease state.

The term “treating: as used herein refers to inhibiting the diseasestate, i.e., arresting the development of the disease state or itsclinical symptoms, or relieving the disease state, i.e., causingtemporary or permanent regression of the disease state or its clinicalsymptoms. The term is interchangeable with any one or more of thefollowing: abrogating, ameliorating, inhibiting, attenuating, blocking,suppressing, reducing, halting, alleviating or preventing symptomsassociated with the disease.

According to one aspect, the present invention provides a compoundhaving the general formula I:

wherein

-   -   A is

-   -   R¹ is independently at each occurrence a halogen, OH, NO₂ or        N(R)₂ wherein each R is independently H or a C₁-C₆ alkyl;    -   R² is COOH, OH, NO₂, N(R)₂ or a linear or branched C₁-C₆ alkyl        substituted with at least one group selected from the group        consisting of COOH, halogen, OH, NO₂, and N(R)₂;    -   R³ is H or COOH;    -   R⁴ is iodophenyl, heterocyclyl, heteroaryl, or the side chain of        an amino acid selected from the group consisting of tyrosine,        3,4-dihydroxyphenylalanine (DOPA), iodotyrosine, aspartic acid,        valine, leucine, isoleucine, methionine, tryptophan, threonine,        asparagine, glutamine, cysteine, proline, arginine, histidine,        lysine, glutamic acid; or R⁴ is represented by the structure:

-   -   wherein R⁵ is independently at each occurrence OH, halogen, NO₂        or N(R)₂ and m is 0, 1, 2, 3 or 4;    -   L¹ and L² are each a leaving group selected from a halogen and a        sulfonate;    -   n is 1, 2, 3 or 4;    -   and salts thereof.

In one embodiment, the compound of formula (I) is a phenylcarboxylicacid derivative (e.g., p-benzoic acid derivative or iopanoic acidderivative), represented by the structure of formula (II):

In another embodiment, the compound of formula (I) is represented by thestructure of formula (III):

Compounds useful in treating and/or preventing any of the diseases orconditions described herein are compounds of formula (I), for examplecompounds of formulae (II) or (III). Additional compounds useful intreating and/or preventing any of the diseases or conditions describedherein are compounds of formula (I-A):

wherein

-   -   A is

-   -   R¹ is independently at each occurrence a halogen, OH, NO₂ or        N(R)₂ wherein each R is independently H or a C₁-C₆ alkyl;    -   R² is COOH, OH, NO₂, N(R)₂ or a linear or branched C₁-C₆ alkyl        substituted with at least one group selected from the group        consisting of COOH, halogen, OH, NO₂, and N(R)₂;    -   R³ is H or COOH;    -   R⁴ is iodophenyl, heterocyclyl, heteroaryl, the side chain of an        amino acid selected from the group consisting of a naturally        occurring alpha-amino acid, 3,4-dihydroxyphenylalanine (DOPA)        and iodotyrosine; or R⁴ is represented by the structure:

-   -   wherein R⁵ is independently at each occurrence OH, halogen, NO₂        or N(R)₂ and m is 0, 1, 2, 3 or 4;    -   L¹ and L² are each a leaving group selected from a halogen and a        sulfonate;    -   n is 0, 1, 2, 3 or 4;    -   and salts thereof.

Preferred embodiments of formula I, I-A and II are compounds of formula3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, as described herein, and saltthereof.

One or more of the compounds of the invention, may be present as a salt.The term “salt” encompasses salts formed by standard acid-base reactionsbetween an acidic moiety and an organic or inorganic cation. The term“organic or inorganic cation” refers to counter-ions for the carboxylateanion of a carboxylate salt or the counter ion for the phenoxide moiety.The counter-ions are chosen from the alkali and alkaline earth metals(such as lithium, sodium, potassium, barium, aluminum and calcium);ammonium and mono-, di- and tri-alkyl amines such as trimethylamine,cyclohexylamine; and the organic cations, such as dibenzylammonium,benzylammonium, 2-hydroxyethylammonium, bis(2-hydroxyethyl)ammonium,phenylethylbenzylammonium, dibenzylethylenediammonium, and like cations.

The present invention also includes solvates of any of compoundsdescribed herein. “Solvate” means a physical association of a compoundof the invention with one or more solvent molecules. This physicalassociation involves varying degrees of ionic and covalent bonding,including hydrogen bonding. In certain instances the solvate will becapable of isolation. “Solvate” encompasses both solution-phase andisolatable solvates. Non-limiting examples of suitable solvates includeethanolates, methanolates and the like. “Hydrate” is a solvate whereinthe solvent molecule is water.

According to another aspect, the present invention provides apharmaceutical composition comprising at least one compound of thepresent invention and a pharmaceutically acceptable diluents or carrier.

As sued herein, the term “pharmaceutically acceptable carrier orexcipient” means an additive, carrier, excipient or diluent which isuseful in preparing a pharmaceutical composition that is generally safenon-toxic, and neither abrogates nor causes otherwise undesirable effectto the administered compound. The term includes such additives that areacceptable for human as well as veterinary pharmaceutical use.

The term “subject” includes humans and animals amenable to therapy witha DIO3 inhibitor including animals afflicted with cancer or depressionor depression associated disease or disorder. According to someembodiments, the subject is a human subject. Each possibility representsa separate embodiment of the invention.

The term “subject” as used herein, includes, for example, a subject whohas been diagnosed to be afflicted with cancer or depression ordepression associated disease or disorder or a subject who has beentreated to ameliorate cancer or depression or depression associateddisease or disorder, including subjects that have been refractory to theprevious treatment. Also encompassed within the present invention is ahealthy subject having a risk of being affected with cancer ordepression or depression associated disease or disorder. According tosome embodiments, the subject is afflicted with cancer and has beenidentified to express DIO3 by the tumor. According to some embodiments,the expression is overexpression and the overexpression is determinedfollowing analysis and comparison with control or reference. Accordingto some embodiments, the control is selected from the group consistingof: a predetermined cutoff value, a value obtained from a healthyindividual, a panel of values from a set of healthy individuals and avalue or a set of values obtained from a group of individuals afflictedwith defined severities of cancer. Each possibility represents aseparate embodiment of the invention. According to yet anotherembodiment, the predetermined cutoff value is obtained from the subjectto be treated at at-least one prior-referenced time point.

According to some embodiments, the expression of DIO3 may be determinedby any method known in the art, for example by an immunoassay.

The pharmaceutical compositions of the invention can be prepared bymethods and contain carriers which are well-known in the art, forexample as described in Remington: The Science and Practice of Pharmacy,Alfonso R. Gennaro, editor, 20th ed. Lippincott Williams & Wilkins:Philadelphia, Pa., 2000.

In general, the compounds of the invention are administered in atherapeutically effective amount by any of the accepted modes ofadministration for agents that serve similar utilities. Suitable dosageranges are depending upon numerous factors such as the severity of thesymptoms to be treated, the age and relative health of the subject, thepotency of the compound used; the route and form of administration; andthe specific indication towards which the administration is directed.One of ordinary skill in the art of treating such conditions will beable, without undue experimentation and in reliance upon personalknowledge and the disclosure of this Application, to ascertain atherapeutically effective amount of the compounds of the presentinvention for a given condition.

Compounds of the invention may be administered as pharmaceuticalformulations including those suitable for parenteral administration(including intramuscular, subcutaneous and intravenous), oraladministration (including buccal and sub-lingual), nasal, topical,pulmonary, intrathecal administration, or administration by inhalation.A preferred manner of administration is generally oral using aconvenient daily dosage regimen which can be adjusted according to thedegree of affliction. According to one embodiment, the DIO3 inhibitor isadministered locally into the tissue to be treated. According to oneembodiment, the tissue is a brain tissue, and the administration routeis directly into the brain tissue.

According to some embodiments, the composition comprising a DIO3inhibitor may further comprise an additional agent. The additional agentmay be any treatment for cancer, depression or depression associateddisease or condition. According to some embodiments, treatment comprisesadministering to a subject in need thereof a plurality of DIO3inhibitors.

A compound or compounds of the invention, together with one or moreconventional adjuvants, carriers, or diluents, may be placed into theform of pharmaceutical compositions and unit dosages. The pharmaceuticalcompositions and unit dosage forms may be comprised of conventionalingredients in conventional proportions, with or without additionalactive compounds or principles, and the unit dosage forms may containany suitable effective amount of the active ingredient commensurate withthe intended daily dosage range to be employed. The pharmaceuticalcompositions may be employed as solids, such as tablets or filledcapsules, semisolids, powders, sustained release formulations, orliquids such as solutions, suspensions, emulsions, elixirs, or filledcapsules for oral use; or in the form of sterile injectable solutionsfor parenteral use.

According to yet additional aspect, the present invention provides amethod for treating or preventing depression or a depression-associateddisease or condition, the method comprises administering to a subject inneed thereof a therapeutically effective amount of a compound thatinhibit the activity of Type III deiodinase (DIO3) thereby treating orpreventing depression a depression-associated disease or condition.

According to certain embodiments, inhibition of the DIO3 activityresults in increased amount of T3 in the subject. According to currentlycertain exemplary embodiments, the amount of T3 is increased in thebrain of the subject.

In some embodiments, the compounds of the present invention are designedto have specificity or some selectivity to inhibition of DIO3, such thatthe other deiodinases (DIO1 and DIO2) are not inhibited or inhibited toa lesser extent. DIO3 is known to be found primarily in the brain, and,more importantly, it is not found in heart or bone tissue. Thus, thespecific inhibition of DIO3 results in increased amount of T3 in thebrain, where it is most required to assert its anti-depressant activity,while having none or negligible of the deleterious side effectsassociated with non-specific elevation of T3 concentration, includingenhancement of bone depletion, muscle weakness and tachycardia (Ocasioand Scanlan, Current Opinion in Endocrinology and Diabetes 2005; 12,363-370; Yoshihara and Scanlan, Curr Top Med Chem 2003; 3, 1601-1616).

In some embodiments, the compounds of the invention also inhibit DIO1and DIO2, in addition to DIO3, but they are designed to selectivelytarget the brain, or they are formulated specifically for braindelivery, such that they target DIO3 selectively due to preferentiallocalization to the brain.

According to yet another aspect, the present invention provides a methodfor treating or preventing cancer, the method comprises administering toa subject in need thereof a therapeutically effective amount of acompound of the present invention.

DIO3 expression and activity have been indicated previously to beassociated with tumorigenesis. Thus, according to further embodimentsthe compounds of the present invention, which inhibit DIO3 are useful astreatment for cancer.

According to some embodiments, the cancer is a solid cancer. Nonlimiting examples of solid cancers which are encompassed within theembodiments of the present invention include pancreatic cancer; bladdercancer; colorectal cancer; breast cancer; prostate cancer; renal cancer;hepatocellular cancer; lung cancer; ovarian cancer; cervical cancer;gastric cancer; esophageal cancer; head and neck cancer; melanoma;neuroendocrine cancer; brain tumors.

According to some embodiment, the cancer is colon cancer or basal cellcarcinoma (BCC).

According to certain exemplary embodiments, the cancer is ovariancancer, endometrial cancer.

According to some embodiments, the compounds of the invention aredesigned to selectively target overproliferating cells, particularlycancer cells, or they are formulated specifically for delivery intothese types of cells such that they target DIO3 selectively due topreferential localization within these cells.

The DIO3 inhibitors of the present invention may be administered by anysuitable route of administration. According to some embodiments, theDIO3 inhibitor is prescribed for a chronic administration. Chronicadministration may be performed, for example, by a single dose, oncedaily. According to some embodiments, the DIO3 inhibitor is prescribedfor acute administration.

The therapeutically effective amount of a compound of the invention tobe administered to a subject depends on the condition to be treated andsubject parameters including, but not limited to, gender, age, weighttype and severity of the condition. The therapeutically effective amountcan be initially assessed from in vitro assays. Target concentrationswill be those concentrations of active compound(s) that are capable ofinhibiting DIO3 activity by at least about 5%-95% in comparison to DIO3activity in untreated cell, either normal or overproliferating cells.Target concentrations of active compound(s) that are capable ofinhibiting DIO3 by at least about 60-70% or even 90% or higher in invitro assays are preferred.

Therapeutically effective amounts for use in humans can also bedetermined from animal models. For example, a dose for humans can beformulated to achieve a circulating concentration that has been found tobe effective in animals. Animal models of cancer and for depressionassessment are known in the art. For treating cancer, the dosage inhumans can be adjusted by monitoring inhibition of cell proliferationand/or tumor growth and adjusting the dosage upwards or downwards, toachieve the desired percentage of inhibition. For treating depression,the dosage in humans can be adjusted in view of the effective dosagethat alleviated or abolishes the depression associated symptoms.Adjusting the dose to achieve maximal efficacy in humans based on themethods described above and other methods as are well-known in the artis well within the capabilities of the ordinarily skilled artisan.

It is to be explicitly understood that any mechanism by which inhibitionof DIO3 activity overcomes depression or depression associated diseaseor disorder is encompassed within the scope of the present invention. Ithas been previously acknowledged that the phenomena attributed to T3 maybe mediated by T3 activation of gene transcription. Accordingly, most ofthe reports regarding the use of T3 as antidepressant describe positiveinfluence of T3 administration after a lag time of about a week.However, other antidepressants are known to have immediate effect. Forexample, ketamine has been reported to have anti-depression activityafter acute administration to humans (Aan Het Rot et al. BiologicalPsychiatry, 2012; 72(7), 537-547), and to affect the behavioralperformance of rats in forced swim test (FST) (Yang C. et al., 2012.Journal of Biomedicine and Biotechnology, Epub 2012 Apr. 8).

It has been also described that in addition to being active by inductionof gene transcription the thyroid gland hormones show immediatephysiological effects. Thus, without wishing to be bound by any specifictheory or mechanism of action, administration of DIO3 inhibitors canassert immediate antidepressant effects.

The following examples are presented in order to more fully illustratesome embodiments of the invention. They should, in no way be construed,however, as limiting the broad scope of the invention. One skilled inthe art can readily devise many variations and modifications of theprinciples disclosed herein without departing from the scope of theinvention.

EXAMPLES Example 1: Design and Synthesis of DIO3 Mimics

To date, pure DIO3 enzyme is not available. An inventor of the presentinvention and co-workers have designed and synthesized molecules thatfunctionally mimic DIO3 in terms of deiodinase activity (Manna et al.,2010, ibid; Manna et al., 2012, ibid). Such DIO3-mimetic molecules havenow been utilized for design and synthesis of compounds capable ofinhibiting DIO3 enzyme. The present invention discloses such compoundsthat functionally inhibit the activity of the DIO3-mimetic molecule andthe wild-type (wt) DIO3 enzyme.

The deiodination of thyroxine by compound A (a DIO3 mimetic; FIGS. 2 and3) in the presence of various thiourea derivatives was studied. When thecommonly used antithyroid drugs such as thiourea derivatives (e.g.,6-n-propyl-2-thiouracil (PTU), 6-methyl-2-thiouracil (MTU) and1-methyl-3H-imidazole-2-thione or methimazole (MMI)) were used, noinhibition of the deiodinase activity was observed. Although PTU and MTUhave been shown to inhibit DIO1, these compounds do not inhibit DIO3.Specifically, thiourea compounds (e.g., PTU) have been shown to reactwith the selenenyl iodide intermediate of DIO1. Those results suggestthat compound A not only deiodinates T4 in the inner-ring, but alsobehaves similarly to DIO3 with respect to inhibition. These studiessuggest that thiourea-based compounds are not suitable as inhibitors forDIO3.

Another known inhibitor of DIO1, i.e. iodoacetic acid (IAA), may reactwith the selenol group of the enzyme. This compound is specific for DIO1and cannot inhibit DIO2 and DIO3. Although IAA can effectively inhibitthe activity of several Cys peptidases (i.e., the Sec-containingglutathione peroxidase (GPx), and thioredoxin reductase (TrxR)) byforming the corresponding alkylated Cys or Sec derivatives, the reasonfor the insensitivity of DIO3 toward IAA is not clear. Treatment ofcompound A with IAA resulted in a deiodination instead of the formationof Se-carboxymethylated derivative. In contrast, a compound that lacksthe second selenol moiety underwent facile carboxymethylation by IAA.These observations suggest that IAA may undergo rapid deiodination inthe presence of DIO3, which may account for the insensitivity of thisenzyme toward IAA.

A careful analysis of the amino acid residues at the active site of DIO3indicates that there is a cysteine (Cys) residue in the enzyme that mayassist the selenocysteine (Sec) in the deiodination reaction. In themimic, the second selenol moiety in the 8-position of the naphthalenering is expected to perform a similar function. The current approachaims at targeting both the Sec and Cys instead of targeting the Secalone. Previous attempts to develop inhibitors for DIO3 based on Secreactivity were unsuccessful.

As described above, it is contemplated that any compound that can reactwith the both selenol moieties simultaneously in the synthetic DIO3mimic of compound A may inhibit the deiodinase activity of thiscompound.

Without wishing to be bound by any particular mechanism or theory, itwas hypothesized that the dibromomaleimide derivatives of the presentinvention may inhibit the activity of the DIO3 mimic by reacting withthe two selenol groups to form a stable adduct.

In view of the above, the following compounds (compound B and C) weresynthesized. The two simultaneous nucleophilic attacks of the selenolmoieties at the carbons adjacent to the carbonyl groups are expected toblock the selenium centers. The reactions of compound A with compounds B(2,3-dibromo-N-benzylmaleimide) and C (2,3-dibromo-N-methylmaleimide)were studied. The reaction of compound A with compounds B and C producedthe adducts D (1,8-bis(2,3-diseleno-N-benzylmaleimide)naphthalene) and E(1,8-bis(2,3-diseleno-N-methylmaleimide)naphthalene).

Subsequently, the deiodination of T4 by compound A in the presence ofcompounds B and C was studied. The results demonstrate that compounds Band C do inhibit the deiodination of T4 (exemplified in FIG. 4 forcompound C).

Another compound, a novel tyrosine derivative 3 (TYR-DBRMD) wassynthesized. The following description demonstrates the route employedfor the synthesis of TYR-DBRMD.

Synthesis of TYR-DBRMD (Compound 3)

The novel tyrosine derivative 3 was obtained from dibromomaleicanhydride (1) and L-tyrosine. As the commercially available startingmaterial (compound 2) is expensive, it was prepared from maleicanhydride (1) in a sealed Teflon tube by using aluminum chloride ascatalyst. For the synthesis of compound 2, the procedure reported inDubernet et al. (Dubernet, M. et al., Tetrahedron, 2005; 61, 4585-4593)was followed:

Synthesis of 3,4-Dibromomaleic anhydride: A mixture of maleic anhydride(2.0 g, 20.39 mmol), aluminum chloride (40.8 mg, 0.3 mmol), and bromine(2.1 ml, 40.78 mmol), was heated at 120° C. for 16 h in sealed tube.After that, it was allowed to cool to room temperature and the reactionmixture was added to ethyl acetate. The ethyl acetate solution wasfiltered and the filtrate was evaporated. To the resulting reddishsolid, 100 ml CHCl₃ was added and filtered. The filtrate was evaporatedto get off-white (yellow) solid in 87% yield. 13C NMR (CDCl3) δ(ppm):131.8, 159.0.

To a solution of 3,4-dibromomaleic anhydride (500 mg, 1.95 mmol) inacetic acid (10 ml), tyrosine (425 mg, 2.35 mmol) was added. The mixturewas heated at reflux condition for 12 h. The solvent was removed underreduced pressure. The crude mixture was purified by columnchromatography over silica gel using petroleum ether and ethyl acetateas mobile phase to afford the desired product (485 mg, 59%) as off-whitesolid.

¹H NMR (DMSO-d₆) δ (ppm): 3.02-3.08 (1H, m), 3.25-3.30 (1H, m),4.90-4.94 (1H, dd, J=8.0 Hz) 6.60 (2H, d, J=8.0 Hz), 6.89 (2H, d, J=8.0Hz) (FIG. 6).

¹³C NMR (CDCl₃) δ (ppm): 33.9, 55.8, 116.1, 127.7, 130.1, 130.6, 156.8,168.4, 170.5 (FIG. 7).

m.p. 175-177° C.

Synthesis of PBENZ-DBRMD (Compound 4):

To a solution of 3,4-dibromomaleic anhydride (500 mg, 1.95 mmol) inacetic acid (10 ml), p-amino benzoic acid (322 mg, 2.35 mmol) was added.The mixture was heated at reflux condition for 12 h. The solvent wasremoved under reduced pressure. The crude mixture was purified by columnchromatography over silica gel using petroleum ether and ethyl acetateas mobile phase to afford the desired product (550 mg, 82%) as yellowsolid.

¹H NMR (DMSO-d₆) δ (ppm): 7.50 (2H, d, J=8.0 Hz), 8.04 (2H, d, J=8.0 Hz)(FIG. 8).

¹³C NMR (DMSO-d₆) δ (ppm): 127.5, 130.6, 130.9, 131.1, 136.0, 163.9,167.6 (FIG. 9).

Example 2: Deiodination Assay

The deiodination reactions were carried out in 100 mM phosphate buffer(pH 7.5) with 10 mM dithiothreitol (DTT) at 37° C. Diselenol (CompoundA) was freshly prepared by reducing the corresponding diselenide, withNaBH₄ prior to use. The reaction products were analyzed by reverse-phaseHPLC (Lichrospher C18 column, 4.6 μm, 150 mm×5 mm) with gradient elutionusing acetonitrile/ammonium acetate (pH 4.0) as the mobile phase. Theformation of rT3 was monitored at λ=275 nm and the amounts ofdeiodinated products formed in the reactions in the presence or absenceof test compounds were calculated by comparing the peak areas.

Inhibition of the DIO3 Mimic by TYR-DBRMD (Compound 3)

Compounds 3 and 4 were selected based on their water solubility. The TYR(tyrosine derivative, compound 3) is more soluble in water (due to thepresence of —OH and —COOH groups) than PBENZ (benzoic acid derivative,compound 4), but the PBENZ is expected to be more lipophilic. Thereactivity of the two compounds toward the DIO3 mimic is was found to besimilar, although they may exhibit different binding behavior with theenzyme. However, the affinity data with the mimic may not correlate withthat of the enzyme, as there will be additional interactions (hydrogenbonding etc) with the inhibitors at the active site of the enzyme, whichare absent with the mimetic molecule.

The two compounds (3 and 4) react stoichiometrically with the mimic. TheIC₅₀ values for inhibiting the DIO3 mimic were found to be in themicromolar range (FIG. 5) as the mimics used were in the micromolarconcentrations for the deiodination of thyroxine. Assuming that in vivo,the enzymes are present in sub-nanomolar concentrations and theinhibitors are expected to form a covalent bond with the enzyme, it isexpected the IC₅₀ values will be in the nanomolar concentration range.

Additional inhibitors of DIO3 contemplated by the present invention arecompounds 5, 6, 7, 8, 9, 10, 11 and 12 presented below. Those compoundscomprise several modifications such as iodine ions (inITYR-DIBRMD—compound 5, and IOP-DIBRMD—compound 6). These compounds canbe stabilized by halogen bonding at the enzyme active sites, caused bythe iodine atoms that are attached to maleimide moiety, thus greaterdeiodinase isoenzyme specificity is supposedly achieved. As DIO3 readilyaccepts iodinated substrates, the introduction of iodine may help thecompounds to bind strongly to the active site. For example, thecommercially available iodine-containing compound, Iopanoic acid (IOP)has been shown to be a substrate for DIO3 (Huang M P et al., Thyroid,2011, 21, 1263).

Example 3: High Throughput Assays for Determining Deiodinase 3Inhibitors Effects on Enzyme Activity

Rapid evaluation of the effects of novel putative deiodinase 3inhibitors on activity levels of DIO3 is established by a high outputsystem employing two main lines of in vitro assays:

1) Mouse brain-derived microsome assay: Mouse brain tissue ishomogenized and centrifuged to obtain microsomal fractions. Proteinconcentration in each fraction pellet is determined by Bradford Assay.Deiodinase 3 activity determination, in the presence of putativedeiodinase inhibitors, is carried out by incubation of a given amount ofthe fraction with the radioligand [3,5-¹²⁵I]T3, each incubation donewith blanks (no protein) to correct for non enzymatic degradation ofradioligand. Reactions are stopped and radioiodide ¹²⁵I emission ismeasured by precipitation of the [¹²⁵I]iodothyronines and isolation ofthe emitted (by the inner ring deiodination reaction)¹²⁵I radioiodide onmicrocolumns. Radioactivity in the eluate is monitored using ascintillation detector.

2) Cell based assay: Astrocytes from neonate mice are harvested and acell suspension is prepared, plated on Petri dishes and maintained in acell incubator. After 7 days, cells are disrupted and homogenates areprepared. In the presence of the putative deiodinase 3 inhibitorcompound, the homogenates is incubated with [¹²⁵I]T3. Reactions arestopped by the addition of NH₄OH containing 10 micro molar T3. The[¹²⁵I]3,3′-T2 produced by deiodinase 3 action is separated from [¹²⁵I]T3by chromatography. Then the radioactive products of the reaction arecounted for determination of D3 activity, expressed as fentomoles of3,3′-T₂ per minute per milligram protein.

Example 4: Effects of Intracerebroventricular (ICV) Administration ofITYR-DIBRMD (ITYR; Compound 5) and IOP-DIBRMD (IOP; Compound 6) onDepression

Materials and Methods:

Chronic Intra-Cerebroventricular (ICV) Administration Via OsmoticMinipumps

The intra-cerebroventricular injection was performed via a cannulainserted as follows: first, for the chronic administration of compoundsor vehicle, osmotic minipumps (Alzet model 1004 for up to 28 daysadministration) were employed. Empty minipumps were filled under sterileconditions with 0.1 ml of PBS or with PBS containing either one of theDIO3 inhibitors and then connected to brain infusion kits. The filledminipumps connected to the brain infusion kits were than primed in anincubator at 37° C. before being implanted into the animals. At thesurgery itself, each mouse was anaesthetized by intraparenteral (i.p.)injection of anesthesia. The anesthesia solution was prepared asfollows: for each 2 ml of solution, 900 μl ketamine plus 100 μl xylazine2% was supplemented with 1000 μl of 0.9% NaCl saline solution. 70 μl ofthe anesthesia solution was administered i.p to a 20 gram (about 100 μlfor 30 gram) weighing animal. After being anesthetized the animal washooked to a stereotactic table. A longitudinal cut was made in the headskin, the upper part of the skull was exposed and a hole was producedusing 0.5 mm diameter drill and the cannula was inserted. The hole waslocated at the following coordinates relative to the bregma:Anterior-ventral-dorsal=2.5 mm; Medial-lateral=1.0 mm andanterior-posterior=0.0 mm. Thereafter each minipump—was insertedsubcutaneously to the interscapular space and the base of the infusionkit cannula was glued, using specialized Loctite adhesive, to the skullbase so the cannula shaft itself will protrude through the drilled holeto the lateral ventricle, and through a catheter linked to ALZET braininfusion kits number 3, the compounds or vehicle wereintracerebroventricullary through the drilled hole.

The wound formed in the skull was sown with silk sutures, and after itawoke, each animal was transferred to the home cage for recovery,typically for 48 h, after which the experiment may be started.

39 male BALB/c male mice aged 8 weeks were implanted with ALZET model1004 osmotic minipumps for intracerebroventricular (ICV) administrationof compounds in 3 treatment groups (13 mice in each group): (1) theputative DIO3 inhibitor IOP-DIBRMD (IOP, compound 6) dissolved inphosphate buffered solution (PBS) vehicle; (2) the putative DIO3inhibitor ITYR-DIBRMD (ITYR, compound 5) dissolved in PBS; (3) PBSvehicle. Minipumps contained 0.1 ml of PBS into which the putative DIO3inhibitors ITYR (5 mg/kg) or IOP (2 mg/kg) were dissolved, or PBSvehicle. 8, 13 and 9 mice survived the experiment in the PBS, ITYR andIOP groups, respectively. Deaths were related to the surgical procedure.After recovery from minipump implantation surgery, animals were returnedto their home cages for continuous ICV compound administration for 3weeks, before behavioral testing commenced.

Assessment of Antidepressant-Like Activity and Serum and Brain ThyroidHormone Levels

Novelty Suppressed Feeding Test (NSFT):

After the last treatment administration, all food was removed from thecage for 24 hours (water was available ad libitum). At the end of thisperiod, each animal was introduced into a 50×50×30 (height) cm plasticarena located in a specialized behavioral room in which all behavioraltests were tracked by cameras linked to a computer installed withEthoVision behavioral tracking software of the latest edition (XT 10). Apellet of food was placed on an elevated surface in the center of thearena. Time elapsing from the introduction of the animal into the arenauntil it commences eating (latency to feed), total distance move,velocity and time spent in the arena periphery (lateral 10 cm on eachside) and center were recorded. The animal was then removed from thearena immediately after it begins to eat or after not doing so for 5min. After the test, the animal was immediately transferred to its homecage and left to consume a previously weighed amount of food for 10minutes. On completion of this period the food was weighed again tocalculate the home cage food consumption. The rating of the animals'behavior was conducted by two experimenters who were blind to thetreatment received by each mouse. The mean of the two ratings wascalculated and used for the statistical analysis.

Serum and Brain Thyroid Hormone Levels

At the end of the tests, animals were anesthetized with veterinaryPental (13.333 mg/kg) and cardiac blood was drawn for peripheral T3(triiodothyronine) and T4 (thyroxine) levels. Brains were harvested forevaluating brain T3, T4 levels. Hormone levels in the sera and brainswere measured by SunLong Biotech Mouse Ultrasensitivity total and freeT3 and T4 ELISA Kits, employing producing a standard curve followed byactual measurement, in which OD levels obtained by spectrophotometerwere converted, using the standard curve, to pg/ml values.

Results

i) Effect of IOP and ITYR on Brain and Serum Hormone Levels

As shown in Table 1 and FIG. 10, IOP treatment for 3 weeks via ICVadministration resulted in a significant increase in brain free T3levels (about 46%). Brain free T3 level was not significantly increasedwhen ITYR was administered. Neither treatment significantly increasedbrain free T4 levels or the levels of either free hormone in the serum.

TABLE 1 Brain and serum hormone levels after treatment with IOP and ITYRBrain Serum Treat- No. of Signif- Signif- ment mice Mean SD icance* MeanSD icance* Free T3 (pg/ml) Vehicle 8 72.74 9.63 14.45 2.83 (PBS) IOP 1084.30 15.31 *0.041 12.23 1.64 NS ITYR 12 81.98 12.24 NS 12.33 1.30 NSFree T4 (ng/ml) Vehicle 8 250.54 53.51 36.05 8.53 (PBS) IOP 10 244.1144.72 NS 35.75 9.79 NS ITYR 12 262.86 32.70 NS 37.00 8.92 NS *One sided,non-paired t test; active compound vs. vehicle

ii) Effect of IOP and ITYR on Latency to Feed in the Novelty SuppressedFeeding Test

The time taken for a rodent to start eating a pellet of food located inthe center of an open field arena (latency to feed) is a reflection ofanxiety level and is also seen as reflecting level of anhedonicbehavior. In the current experiment, treatment with both IOP and ITYRresulted in a reduced latency to feed compared to mice treated withvehicle (FIGS. 11 and 12, respectively). Data were analyzed by analysisof covariance with brain T3 level entered as the covariate. The effectof T3 in mice treated with both IOP and ITYR was found to besignificant.

Example 5: Effect of DIO3 Inhibitors on Ovarian Cancer Cells

Cell Lines:

Human ovarian adenocarcinoma cells employed in the study were OVCAR-3(ATCC HTB-161), A2780 (Sigma Aldrich) and SKOV-3 (ATCC HTB-77). Humannormal embryonic kidney cells, HEK 293 (ATCC CRL1573) were used. Allcells were cultured in RPMI1640 supplemented with 10% heat-inactivatedFBS and antibiotics. Before conducting an experiment, cells werecultured for 24 h in RPMI1640 supplemented with 1.5% heat-inactivatedcharcoal stripped FBS and antibiotics.

Flow Cytometry (MACSQuant, Miltenyi):

The cells were treated with 70% ethanol at −20° C. for 1 hour, stainedwith rabbit anti Human DIO3 monoclonal antibody (Alexa Fluor® 647) fromNovus Biologicals and analyzed for endogenous DIO3 level by FACS.

Viability:

WST-1 (Roche; 10% final concentration) was incubated with cells at 37°C. for 2 h and read with a MicroELISA reader at 440 nm.

Microscopy:

The cells were visualized using a microscope equipped with a camera(model IX71; Olympus) with a 20_/0.50 objective lens and Cell{circumflexover ( )}A (version 3.1) Olympus software imaging.

Compounds

The following DIO3 inhibitory compounds were examined: PBENZ (compound4); TYR (compound 3); IOP (compound 6); ITYR (Compound 5): DOP (compound7) and ASP (compound 8).

The anti cancerous (anti-proliferative) effect of the DIO3 inhibitorsdescribed above was examined using the above-described human ovariancancer cells (OVCAR3, SKOV3 and A2780). The cells were cultured in RPMI1640/10% PBS/antibiotics.

T3 influences cellular growth, differentiation and apoptosis, and thusits level within cells is strictly regulated. Elevated DIO3 levels andthus reduced T3 levels are favorable to the neoplastic process.Therefore, cancer cells that show elevated DIO3 are a good model fortesting the potential anti-neoplastic efficacy of DIO3 inhibitors.Accordingly, the level of endogenous DIO3 protein in the differentcancer cells was assessed by FACS analysis using monoclonal antibodyagainst the human DIO3. Results indicate that OVCAR3 cells exhibited thehighest DIO3 protein level (FIG. 13A) and this cell type was used as theexperimental model.

OVCAR3 cells were collected and seeded in 96 well plates (10,000/well).The six compounds were then dissolved in DMSO and added to a final 0.5μM concentration for 48 h of incubation. After incubation the cells wereimaged by light microscopy (FIG. 13B). A marked reduction in celldensity and deformed cell morphology was observed with three agents,ITYR, DOP and ASP. These cells were then examined for cell viability byWST-1 assay (FIG. 13C). No effect was evident using PBENZ, a lowreduction in viability was observed using TYR and IOP and a significantreduction in cell viability by the same 3 agents described above, ITYR,DOP and ASP was shown.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the invention that others can, by applyingcurrent knowledge, readily modify and/or adapt for various applicationssuch specific embodiments without undue experimentation and withoutdeparting from the generic concept, and, therefore, such adaptations andmodifications should and are intended to be comprehended within themeaning and range of equivalents of the disclosed embodiments. It is tobe understood that the phraseology or terminology employed herein is forthe purpose of description and not of limitation. The means, materials,and steps for carrying out various disclosed functions may take avariety of alternative forms without departing from the invention.

The invention claimed is:
 1. A compound represented by the structure offormula (I):

wherein A is

R¹ is independently at each occurrence a halogen or OH; R² is OH or alinear or branched C₁-C₆ alkyl substituted with COOH; R³ is H or COOH;R⁴ is iodophenyl, tetrahydrofuryl, or the side chain of an amino acidselected from the group consisting of tyrosine,3,4-dihydroxyphenylalanine (DOPA), iodotyrosine and aspartic acid; or R⁴is represented by the structure:

wherein R⁵ is independently at each occurrence OH or halogen, and m is0, 1, 2, or 3 or 4; L¹ and L² are each bromine; n is 1, 2, 3 or 4; andsalts thereof.
 2. The compound according to claim 1, which isrepresented by the structure of formula (II)


3. The compound according to claim 2, wherein: (a) R¹ is halogenselected from the group consisting of bromine and iodine; or (b) R¹ isOH; or (c) R¹ is iodine and n is 2 or 3; or (d) R² is OH, and thecompound is a phenol derivative; or (e) R² is —CH₂CH(COOH)CH₂CH₃, andcompound (II) is an iopanoic acid derivative.
 4. The compound accordingto claim 1, which is represented by the structure of formula (III)


5. The compound according to claim 4, wherein R⁴ is represented by thestructure:

wherein R⁵ is OH or halogen, and m is 0, 1 or
 2. 6. The compoundaccording to claim 5, wherein (a) R⁴ is the side chain of tyrosine,3,4-dihydroxyphenylalanine (DOPA) or 3,5-diiodotyrosine; or (b) m is 0;or (c) m is 2, and R⁵ is iodine.
 7. The compound according to claim 4,wherein R⁴ is selected from the group consisting of the side chain ofaspartic acid (—CH₂—COOH), iodophenyl and tetrahydrofuryl.
 8. Thecompound according to claim 1, which is selected from the groupconsisting of:

and salts thereof.
 9. The compound according to claim 1, whichselectively inhibits the activity of a Type III deiodinase (DIO3).
 10. Acompound selected from the group consisting of:

and salts thereof.
 11. A pharmaceutical composition comprising acompound according to claim 1, and a pharmaceutically acceptable carrieror excipient.
 12. A method for inhibiting the activity of a Type IIIdeiodinase (DIO3) enzyme, comprising the step of contacting the enzymewith an effective amount of a compound according to claim 1, or apharmaceutical composition comprising such compound.
 13. A method fortreating depression, the method comprises administering to a subject inneed thereof a therapeutically effective amount of a compound thatinhibits the activity of Type III deiodinase (DIO3) according to claim1, or a pharmaceutical composition comprising same, thereby treating thedepression.
 14. The method according to claim 13, wherein the depressionis associated with a condition selected from the group consisting ofmajor depressive disorder, bipolar disorder, dysthymia, posttraumaticstress disorder, post-partum depression, schizophrenia, schizoaffectivedisorder, anxiety disorder, Parkinson's disease, Alzheimer's disease,eating disorder, fibromyalgia, chronic fatigue syndrome, alcohol abuseand drug abuse.
 15. The method according to claim 13, wherein inhibitionof the DIO3 activity results in increased amount of T3 in the subject,preferably wherein the amount of T3 is increased in the brain of thesubject.
 16. A method for treating a subject affected with orsusceptible to be affect with at least one condition or disorderselected from the group consisting of obsessive compulsive disorder,panic disorder, generalized anxiety disorder, pre-menstrual syndrome(PMS), posttraumatic stress disorder, social phobia, agoraphobia,fibromyalgia, chronic fatigue syndrome, chronic pain, bulimia, anorexianervosa, obesity, alcohol abuse, smoking cessation and nicotinewithdrawal syndrome symptoms, the method comprises administering to thesubject a therapeutically effective amount of a compound that inhibitsthe activity of Type III deiodinase (DIO3) according to claim 1, or apharmaceutical composition comprising same.
 17. The method according toclaim 16, wherein inhibition of the DIO3 activity results in increasedamount of T3 in the subject, preferably wherein the amount of T3 isincreased in the brain of the subject.